Propagation of plants



Patented Aug. 15, 1939 g I 2,169,549

UNITED STATES PROPAGATION OF PLANTS Percy W. Zimmerman and Albert E. Hitchcock, Yonkers, N. Y., asslgnors to Boyce Thompson Institute for Plant Research, Inc., Yonkers, N. Y., a corporation of New York No Drawing. Application March 17, 1937,

' Serial No. 131,371

10 Claims. (01. 47-58) This invention relates to the propagation of have found of special advantage in the practice of plants from cuttings, and has for its object the the invention are salts of phenylacetic acid and provision ofan improved method for inducing esters of phenylacetic acid. Thealkali metal salts root-growth on such cuttings. This application (including the ammonium salt) and the alkaliis a continuation in part of our copending appliearth metal salts of phenylacetic acid in general cation Serial No. 72,058, filed April 1, 1936. are the preferred salts for use in carrying out the It has heretofore been recognized that certain invention. The lower alcohol esters (such as the gases (e. g.,' ethylene) induce definite types of methyl and ethyl esters) of phenylacetic acid formative responses on plants, such as stimulation constitute the preferred esters for use in carrying I0 or retardation of the growth of certain tissues, out the invention. So far as we have now deterand the initiation of cell division which results in mined, however, all of the salts and esters of various kinds of proliferations or in the formaphenylacetic acid possess definite powers of intion of roots. As a result of an exhaustive inducing root-growth and similar plant physiolog= vestigation of the effects of various types of ical responses on cuttings and the like.

Fries growth substances on plants, we have discovered Treatment of the more succulent type of plants, 15

'that certain organic compounds exercise a prosuch as the tomato, African marigold, tobacco, nounced stimulating effect on root-growth, and etc., with the growth substances of the present are highly valuable in promoting and inducing invention (i. e., phenylacetic acid and its derivroot-growth on plant slips or cuttings. In this atives) has shown that roots maybe induced to specification and in the appended claims, the word grow from any portion of the stem, and even 20 cutting" and the expression cuttings and the from the leaves of many species. The growth sublike" are used generically to designate any part stance may be mixed with lanolin, olive oil, parafof a plant, including buds, scions, and slips, used fin oil, maize oil, castor oil, "Amalie oil (a comfor purposes of propagation, and the invention mercial mineral oil) and the like, and a thin film 26 advantageously may be employed to promote of the mixture may be applied by rubbing with a 2 plant propagation from any such plant part by glass rod on the epidermis of the region to be inducing active callus formation, root-growth, treated. The usual concentrations found most and similar plant physiological responses. effective are from about 0.01 to 2% of the growth Among, the organic compounds which we find substance on the weight of lanolin or the like;

30 useful for inducing root-growth are phenylacetic Lanolin and similar preparations of the growth 30 acid and its derivatives. In the appended claims substance may be applied directly to the cutting, these compounds are defined generically as comor they may be placed on shoots which remain atpounds in which the phenyl radical is substituted tached to the parent plant during the period of for one of the hydrogen atoms attached to the treatment and are then removed and made into 36 terminal carbon atomfarthest from the carboxyl cuttings that are handled at this stage the same group of a compound having the acetic acid as is normally done in commercialpractice. When structure as its nucleus, that is, the acetic acid applied to the stems, the growth substances of structure (which does not include the acid hydrothe present invention definitely cause local initiagen atom of acetic acid itself) is the base or tion of roots on growing plants of ton1ato, 'sun 4o foundation of the molecule of the compound. flower, marigold, artichoke, buckwheatfdahlia, 40

Based on the foregoing discovery, our present and tobacco. If the plants are lrept in a glass invention involves the improvement in propagatcase afterftreatment, the new roots force their ing plants from cuttings which comprisesthe step way through the epidermis and out into the of inducing root-growth by subjecting the cut-' humid atmosphere. The time required for rootsting to the action of a substance of the group to make their appearance varies with the growth 45 consisting of phenylaoetic acid and its derivatives. substance used, the. concentration, the species Only a minute amount of the substance is necesof plants, andthe exact place on the plant where sary to induce vigorous root-growth and high the material isapplied. V concentrations are usually injurious rather than Phenylacetic acid itself is especially effective 5o beneficial. I for initiating roots on both stems and leaves.

Phenylacetic acid itself is an especially satis- In-the case of phenylacetic acid itself, a 0.01 to factory substance for use in the practice of our 2.0% solution in lanolin causes 'negativ'e (away invention, but derivatives of phenylacetic acid in from side where substance was applied) bending general may be employed with success. Among of tomato stems. Positive (toward side where thederivatives of phenylacetic-acid which we substance is applied) bending occurs when the 56 concentration of the substance is high enough to injure the tissue or, retard the normal rate of growth. A 0.1 to 2.0% solution' of phenylacetic acid in general is optimum for inducing adven-- titious roots.

In general, it might be stated that the most effective concentration for root initiation falls just below that causing positive bending of the stem,

or at the point where there is slight retardation of growth. When the concentration is high enough to cause evident injury,roots appear on the opposite side or adjoining the place on the stem where the substance is applied. This result indicates that as the growth substance diffuses away from the point of toxic concentration a range is reached which is eifective for inducing roots. Under favorableconditions, 15 to 40 mg. of phenylacetic acid per gram of lanolin causes roots to be induced and appear through the epidermis on tomato in six days, marigold in five days, tobacco.

- in eight days, and artichoke in six days.-, Five milligrams of phenylacetic acid per gram of lanolln are eflective, but usually require about -two days more to induce roots.

In commercial practice, treatment of the cutting or parent plant with a water solution of the growth substance is generally more satisfactory and applicable than treatment with lanolin (and similar) preparations. Thus, the. growth substance may be dissolved inthe water (in which it is only sparingly soluble), and the basal end terns.

stance in the aqueous solution is relatively.

of the plant cutting placed'in the solution. The basal end of the cutting immersed in such a solution for from several hours to'several days induces subsequent growth of excellent root sys- The concentration of the growth subminute, say a few milligrams per cc. of water.

Thus, solutions containing 5 to 40 mg. of phenylacetic acid per 100 of water give satisfactory results for many species.- 7

In practicing the invention with water solutions of the growth substances, the plant cutting' is placed in the solution for a period of time ranging from'a few hours to several days. The cutting, after treatment in the solution, may be planted in a mixture of half sand and half peat moss, for example, or in soil. The effectiveness of the treatment is indicated in many ways, such as the increased percentage of rooted cuttings,"

These results are of special significance since cuttings of American holly-are difllcult to root; A similar favorable response to treatment with water solutions of phenylacetic acid was obtained with Japanese maple at the end of six to ten weeks, Japanese holly (Ilea: crenata) at the end .of about four weeks, Taxus at the end of eight to ten weeks, American elm at the end of four to six weeks, and with many other genera and species at the end-of periods ranging from two to ten weeks. I

The derivatives of phenylacetic acid referred to herein as growth substances of the invention are those compounds in which an atom other than a hydrogen atom or a radical has been substituted for the acid phenylacetic acid.

We claim: I 1.The improvement in propagating plants from cuttings and the like which comprises the hydrogen atom oi the step of inducing root-growth by subjecting the" cutting to the action of a compound in which the phenyl radical is substituted for one of the hydrogen atom'sattached to the terminal carbon farthest from the carboxyl group of a compound having the acetic acid structure as its nucleus. i

2. The improvement in propagating plants from cuttings and the likewhich comprises the step of inducing root-growth by subjecting the cutting to the action of phenylaceticacid.

3. The improvement in propagating plants from cuttings andthe like which comprises the step of inducing root-growth by subjecting the cutting tothe action of an alkali metal salt of phenylacetic acid.

4. The improvement in propagating. plants from cuttings and the like which comprises the step of inducing root-growth by subjecting the cutting to the action of a lower alcohol ester of phenylacetic acid. v v

5. The improvement in propagating plants from cuttings and the like which comprisesthe step of inducing root-growth by subjecting the basal end of the cutting to the action of a sub- .stance ,of the group consisting of phenylacetic acid-salts of phenylacetic acid. and esters of phenylacetic acid.

6. The improvement in propagating plants from cuttings and the like which comprises the step of inducing. root-growth by subjecting the basal end ofqthe cutting to the action. of phenylacetic acid.

7. The improvement in propagating plants from cuttings and the like which comprises the step of inducing root-growth by subjecting the basal endof the cutting to the action. of an alkali metal salt of phenylacetic acid.

- 8. The improvement in propagating plants from'cuttings and the like which comprises the step of inducing root-growth by subjecting the.

basal end of the cutting to the action oi a lower alcohol ester of phenylacetic acid.

9. The improvement in propagating plants from cuttings and the like which comprises the step of inducing root-growth by immersion treatment of the basal end of the cutting in an aqueous solution containing phenylacetic acid.

10. The improvement in 'propagatlng plants from cuttings and the like which comprises the step of inducing root-growth by immersion treatment of the basal end of the cutting in an aqueous solution containing an alkali metal salt of phenyl- V acetic acid. i

PERCY w. znvnmmum. ALBERT, E. HITCHCOCK. 

